Reducing agent pyrolysis system for selective catalytic reduction apparatus

Abstract

A reducing agent pyrolysis system for a selective catalytic reduction apparatus includes an elbow duct that is installed on an exhaust duct at a front end of a reactor, allows exhaust gas to flow into the elbow duct, and allows the inflow exhaust gas to be discharged toward the reactor. An inner pipe unit is disposed in the elbow duct, and allows a part of the exhaust gas to flow into and be discharged from the inner pipe unit. A heating device is installed in the inner pipe unit, and heats the exhaust gas flowing into the inner pipe unit. A nozzle is installed in the inner pipe unit, is disposed at a rear end of the heating device based on a flow of the exhaust gas, and injects a reducing agent into the inner pipe unit.

The invention claimed is: 
     
       1. A reducing agent pyrolysis system for a selective catalytic reduction apparatus, the reducing agent pyrolysis system comprising:
 an elbow duct, which is installed on an exhaust duct at a front end of a reactor, allows exhaust gas to flow into the elbow duct, and allows the exhaust gas to be discharged toward the reactor; 
 an inner pipe unit, which is disposed in the elbow duct and allows a part of the exhaust gas to flow into and be discharged from the inner pipe unit; 
 a burner or electric heater, which is installed in the inner pipe unit and heats the exhaust gas flowing into the inner pipe unit; 
 a nozzle, which is installed in the inner pipe unit, is disposed at a rear end of the burner or electric heater based on a flow of the exhaust gas, and injects a reducing agent into the inner pipe unit; and 
 a valve unit, which is installed at a portion of the inner pipe unit where the exhaust gas flows in, 
 wherein a flow rate of the exhaust gas flowing into the inner pipe unit is controlled by controlling an opening and closing operation of the valve unit. 
 
     
     
       2. The reducing agent pyrolysis system of  claim 1 , wherein the elbow duct has a first main pipe and a second main pipe that are disposed and connected at a right angle or an obtuse angle, and wherein the first main pipe and the second main pipe have a greater size than an exhaust duct. 
     
     
       3. The reducing agent pyrolysis system of  claim 2 , further comprising:
 an orifice unit, which is positioned in the first main pipe, 
 wherein an end of the inner pipe unit is disposed inside an opening of the orifice unit. 
 
     
     
       4. The reducing agent pyrolysis system of  claim 1 , further comprising:
 a mixer unit, which is installed at a portion of the inner pipe unit where the exhaust gas is discharged, 
 wherein the reducing agent and the exhaust gas are mixed by the mixer unit. 
 
     
     
       5. The reducing agent pyrolysis system of  claim 4 , wherein the mixer unit is coated with an oxidation catalyst. 
     
     
       6. The reducing agent pyrolysis system of  claim 1 , wherein the exhaust gas flowing into the inner pipe unit is heated to 450° C. to 600° C. by an operation of the burner or electric heater. 
     
     
       7. The reducing agent pyrolysis system of  claim 1 , wherein the reducing agent is a urea solution, and the urea solution is thermally decomposed into ammonia (NH 3 ) and isocyanic acid (HNCO) in the inner pipe unit. 
     
     
       8. The reducing agent pyrolysis system of  claim 1 , wherein when a temperature of the exhaust gas flowing into the elbow duct is higher than a preset temperature, the burner or electric heater is not operated, and the reducing agent is injected toward the reactor. 
     
     
       9. The reducing agent pyrolysis system of  claim 3 , further comprising:
 a mixer unit, which is installed at a portion of the inner pipe unit where the exhaust gas is discharged, 
 wherein the reducing agent and the exhaust gas are mixed by the mixer unit. 
 
     
     
       10. The reducing agent pyrolysis system of  claim 9 , wherein the mixer unit is coated with an oxidation catalyst.